My guess is racism is in the eyes of the offended. You don't have to intentionally do something racist for it to be perceived as racist. Just look at how often "American Inventor" is tossed around here by people who sincerely claim not to be racist ("It's a joke!"/"It's a word!"/"We're taking the power away!"/etc).
If you think that's not fair, you might have a point. But in the end being racist (whether intentionally or not) is not illegal. People can act in ways that they know will be perceived as racist and people will call them racist, but so what? As has been said many times, nobody has a right to not be offended. Whoever dressed up as Crazy Eyes might not have meant it to be racist, but she had to have known that black face is more often than not perceived to be racist. She did it anyway, as is her right, and a bunch of people apparently got offended, which is their right. No laws were broken and whatever consequences this girl will have to face will be due to a shitty judgment call on her part, which is a part of life. We all have to face the consequences of shitty decisions, including doing perfectly legal things that piss other people off.